Gitea docker container's SSHD fails due to missing MaxStartups and MaxSessions in sshd_config

[sutusa]

• Gitea version (or commit ref): 1.15.0+dev-375-g072df3ff8 built with GNU Make 4.3, go1.16.4 : bindata, timetzdata, sqlite, sqlite_unlock_notify
• Operating system: docker image

Today, I bounced the docker container/image using gitea/gitea:latest in my kubernetes configurations. The container log showed that sshd fails to start due to Missing MaxStartups spec on line 8. I was no longer able to communicate to gitea on ssh as suspected:

$ kubectl get pods
NAME                     READY   STATUS    RESTARTS   AGE
gitea-6b7b9c8f79-4kv6t   1/1     Running   0          22m

$ kubectl logs pod/gitea-6b7b9c8f79-4kv6t | head -n 30
/etc/ssh/sshd_config line 8: Missing MaxStartups spec.
/etc/ssh/sshd_config line 8: Missing MaxStartups spec.
/etc/ssh/sshd_config line 8: Missing MaxStartups spec.
2021/06/01 17:58:01 cmd/web.go:81:runWeb() [I] Starting Gitea on PID: 16
2021/06/01 17:58:01 ...dules/setting/git.go:101:newGit() [I] Git Version: 2.30.2, Wire Protocol Version 2 Enabled
2021/06/01 17:58:01 cmd/web.go:125:runWeb() [I] Global init
2021/06/01 17:58:01 ...dules/setting/git.go:101:newGit() [I] Git Version: 2.30.2, Wire Protocol Version 2 Enabled
2021/06/01 17:58:01 routers/init.go:134:GlobalInit() [T] AppPath: /app/gitea/gitea
2021/06/01 17:58:01 routers/init.go:135:GlobalInit() [T] AppWorkPath: /app/gitea
2021/06/01 17:58:01 routers/init.go:136:GlobalInit() [T] Custom path: /data/gitea
2021/06/01 17:58:01 routers/init.go:137:GlobalInit() [T] Log path: /data/gitea/log
2021/06/01 17:58:01 routers/init.go:49:checkRunMode() [I] Run Mode: Prod
/etc/ssh/sshd_config line 8: Missing MaxStartups spec.
/etc/ssh/sshd_config line 8: Missing MaxStartups spec.

I executed a shell within the container and looked at the sshd_config, and it has empty values for MaxStartups and MaxSessions as the log indicated:

$ kubectl exec --stdin --tty gitea-6b7b9c8f79-4kv6t -- /bin/bash
bash-5.1# cat /etc/ssh/sshd_config | head -n 12
Port 22
Protocol 2

AddressFamily any
ListenAddress 0.0.0.0
ListenAddress ::

MaxStartups
MaxSessions

LogLevel INFO

Went looking through recent changes to the gitea code here on github and found this commit from 14 hours ago where MaxStartups ${SSH_MAX_STARTUPS} and MaxSessions ${SSH_MAX_SESSIONS} were just added to the sshd_config in the following commit:

5de01e2

I didn't investigate any further, but the environment variables of SSH_MAX_STARTUPS and SSH_MAX_SESSIONS appear to not have defaults preset and sshd_config values ultimately come up empty.

Thanks.

[sutusa]

I submitted this issue before I knew about this pull thread discussing a potential fix:
#16009